Graduate Studies


First Advisor

Wei Niu

Date of this Version



A THESIS Presented to the faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Chemical Engineering, Under the Supervision of Professor Wei Niu. Lincoln, Nebraska : July 2019

Copyright 2019 Howard Willett

A public-access version of this thesis is now available at


Current industrial synthesis of adipic acid is nonrenewable and depends on a carcinogenic starting material, benzene. Biocatalysis with an engineered microorganism could turn a renewable feedstock into a value-added chemical such as adipic acid. Here we engineered P. putida KT2440 to transform lignin-derived aromatics, coumarate and ferulate, into adipic acid. Lignin is a recalcitrant plant biopolymer burned for thermal energy. Conversion of lignin into a value-added chemical will improve the efficiency of lignocellulose processing plants. The best performing engineered KT2440 strain produces 2.52 mM adipate at a 9.5% (mole/mole) yield. This was achieved by the genetic insertion of non-natural biosynthetic pathway comprised of three enzymes and the deletion of endogenous β-ketothiolase enzymes.

Advisor: Wei Niu